Manufacture and production of soap



Patented Sept. 17, 1929 UNITED STATES PATENT OFFICE ARTHUR EDWARD HATFIELD, OF LEYTONS' IONE, AND EUSTACE ALEXANDER ALLIOTT, 0F GREENBANK, CHESHAM BOIS, ENGLAND MANUFACTURE AND PRODUCTION OF SOAP No Drawing. Application filed June 11, 1927, Serial No. 198,300, and in Great Britain February 15, 1927.

The present invention relates to the manu facture and production of soaps more especially intended for use in dry cleaning work though certain modifications are applicable to laundry work and other cleaning processes. In all processes of cleaning or washing it is very desirable that the soaps employed should be of good solubility and high emulsifying power in order that the soaps, together with the emulsified foreign matter and dirt. can be easily removed from the fibre by subsequent rinsings. This is probably more important in dry cleaning operations than in laundry washing. It has been proved that soaps of poor solubility and low en'iulsifying power in cleaning fluids are apt to retain the already released dirt and redistribute this in the materials. A somewhat similar effect is noticeable in laundry washing where killed soap withassociated dirt may he redeposited on the fibre.

This condition is particularly experienced in dry cleaning white and cream woollens and results in what is known as lead-coloured or greyed whites. Furthermore particularly when local treatment of the articles is necessary, such as removing stains of a water soluble nature, the application of water dissolves the soap. which has been deposited on the material on account of its poor solubility in a dry cleaning fluid. and causes dirt rings. or sweals. This necessitates the en'iployment of drastic aft-er treatment which in most cases results in deterioration of the materials or fibres.

T hese troubles occur because the dry-cleaning soaps in general use at present are made from unsuitable varieties of oleic acid or oleine, or other fatty materials which are saponified in known manner, that is to say, with aqueous solutions of ammonia, potash or soda and the like. Proper attention has not hitherto been given to the purity and particularly the melting point of the fatty acid or mixtures of fatty acids sold or employed under these names or contained in the fats used and such products having setting points of 70 degrees Fahrenheit and often much higher have been considered suitable. (The term setting point is employed to that is to say, such soaps are not perfectly soluble in all dry-cleaning solvents as benzene. gasoline and other petroleum or coal' tar dry-cleaning liquids-and cannot therefore be easily washed from the materials with their associated dirt by the necessary rinse l quors. Comparatively low temperatures, in the region of the setting point of the fatty acid employed, i. e., 36 to F. cause such soaps to be deposited from solution and this is the source of the various troubles mentioned.

l/Vehave found that soaps as prepared by the process hereinafter described do not produce the above-mentioned difficulties as they are of much improved solubility and are easily removed from the fibres, improved dry cleanmg being thereby obtained. It is possible to associate comparatively large amounts of water in close combination with the soaps to be described and this helps to reduce subsequent labour in spotting, by assisting in the removal of water soluble stains, which would not otherwise be touched by washing in dry-cleaning fluid. This also effects a further improvement in dry cleaning practice. The soaps also are able to emulsify free water in the goods'or cleaning fluid. Special types of the soaps hereinafter described give very satisfactory results in laundry work, in view of their higher emulsifying power in the dry-cleaning. Such soaps are particularly useful where a soap containing quantities of dry-cleaning fluid is required for use in water since large volumes of the cleaning fluid may be linked intimately with them to form valuable soap compounds.

A test for solubility in dry-cleaning fluids such as those mentloned above which we have used is to dilute one portion of the soap in not less than 500 parts (preferably 1,000 parts or more) of the solvent. With the soaps prepared acoordin to this invention dissociation does not ta e place in the sample after standing for twenty-four hours at a low temperature (that is to say, approximately the setting point of the fatty 'acid used) in some cases as low as 32 Fahrenheit. We have found also that, after goods have been cleaned by soaps of thischaracter and thoroughly rinsed with soap-free solvent, the materials are free from soap and no trace of foreign matter can be extracted even when employing solvents having superior grease extracting qualities such as ether, and the like.

l/Ve have discovered that the production of soaps of such high solubility in dry-cleaning solvents particularly those mentioned above is dependent on two factors. The first is the quality of the fatty acid employed, which should in general be such that no crystallization or setting of the more solid fatty components takes place above 36 Fahrenheit and it is preferable that the crystallization temperature should be below 31 Fahrenheit 'but in certain cases more fully described hereinafter it may be as high as 50 Fahrenheit. The second is the nature vents of the carrying or stabilizing agent which should be associatedwit-h the soap to maintain it in a properly soluble condition.

It may be mentioned here that a stabilizing agent is a substance added to the soap which nables it to combine with water and still remain in solution in the dry-cleaning fluid. The stabilizing agent prevents the ordinarily unstable emulsion, formed when the soap comes in contact with the article 'being washed, from precipitating and leaving the dirt upon the articles which are being washed.

According to this invention the soaps are prepared by wholly or partially saponifys ing a fatty acid (or mixture of fatty acids) of which the setting point is in general below 36 Fahrenheit, preferably below 31 Fahrenheit, with aqueous solutions of ammonia, or of the carbonates or hydroxides of potassium or sodium and incorporating a stabilizing agent therewith, before, during, or after saponification. A suitable fatty acid is practically pure oleic acid. In certain cases more fully described hereinafter, the setting point of the fatty acids may be as high as 50 Fahrenheit. This primary soap may be associated with an excess of the fatty acid, for example 25 to 35 per cent on saponification, and an organic vola tile liquid solvent which in conjunction with the free fatty acid acts as a stabilizing agent. Such a stabilizing agent is, for instance, alcohol or methylated spirit. In this case the setting point of the"fatty acid is of particular importance since if the fatty acid is such that it will crystallize out in solution before the lower temperatures are reached the free or unsaponified fatty acid associated with the soap will 'also bring down with it the major portion of the saponified fatty ,acids, when the critical temperature is reached. The $11 ernatant liquor will then only contain unc anged fatty acid, which is valueless as soap.

Instead of part or the whole of free fatty acid and alcohol a suitable proportion of chlorinated hydrocarbons may be associated as a stabilizing agent with the soap so that a perfectly soluble dry-cleaners solvent soap of high emulsifying ower is obtained. Among the chlorinated ydrocarbons useful for this purpose may be specified pentachlorethane, trichlorethylene, perchlorethylene.

A still more valuable stabilizing agent of high emulsifying power, which is preferable to the chlorinated hydrocarbons, is cyclohexanol. Good results may be obtained however, with a mixture of cyclohexanol and one of the chlorinated" hydrocarbons mentioned above, articularly perchlorethylene. When cyclo exanol is used the setting point of the fatty acid is of smaller consequence and may be as high as 60 Fahrenheit although .in any case fatty acids of the lower setting points specified are preferable.

In the case of a mixture of fatty acids, we mean by setting point, the temperature at, which the more solid components dissociate from the major portion of the liquid, producing a cloudiness or deposit. lVe determine this temperature by placing the fatty acids melted at as low a temperature as possible in a glass tube 10 to 12 centimetres long and 1 to 2. centimetres wide.

his is suspended in afiask by a perforated cork through which a suspended thermometer passes. The fatty acids are allowed to cool slowly and are stirred for a moment with a thermometer at the first appearance of cloudiness or crystallization and the thermometer is then read and the temperature recorded as a setting point. Any other reliable method of determining the setting point may be used.

Care should be taken that the soap does not contain free akalinity, which might tend to damage the colours of certain goods. When cyclohexanol is used no unchanged fatty acids should be present as they would be useless.

A soap manufactured and associated with emulsifying agents as described may have a proportion of water or spirit dry-cleaning fluid linked with it so intimately as to form a substantiall inse arable compound. This is particu arly t e case when cyclohexanol is used.

If water be associated with the soap the mixture or compound is soluble in dry-cleaning fluid and acts in such a manner that water soluble stains are removed from the goods without the disadvantages which occur from the presence of free water in the cleaning fluid. If cleaning fluid or solvent be associated with the soap, a water soluble compound is obtained except in the case of soap containing free fatty acid, by means of which cleaning fluid or solvent soluble stains can be removed in a general process of washing by means of water. Such water soluble compounds are most useful when cyclohexanol is used.

Hence, by slight modifications in the methods of manufacture, soaps may be obtained which are of special value for dry cleaning on the one hand or for laundry washing on the other hand.

The following examples will further illustrate how the invention may be carried out in practice, but the invention is not limited to these examples.

E trample 1 In the preparation of ,100 pounds of a soap which will be soluble in dry-cleaning solvents and in which 25 to 35% of the fatty acids is left unsaponified, the ingredients should be in the following amoi1nts:--

70.58 pounds of pure oleic acid (known as special pale or'special frozen oleic acid 99.5 per cent to 100 per cent pure, or any similar oleic acid or oleine having a melting point of less than 36 Fahrenheit and preferably less than 31 Fahrenheit) are placed in a jacketed mechanical mixer and raised to a temperature of at least 170 Fahrenheit. To this is added slowly with agitation an aqueous solution containing 12.5 pounds of pure potassium carbonate (09.5 to 100 per cent pure) or an equivalent amount of sodium carbonate or the hydroxides of potassium or sodium or of ammonia liquid of sp. gr. 0.880. The solid alkalis should be previously dissolved in 8 pounds of boiling'water. The alkaline solution should be added slowly with agitation until all the fatty acids are saponified to the extent of to per cent. Considerable ebullition takes place during saponification. but this may be controlled byadding a little alcohol or industrial methylated spirit during the process. Agitation is continued until the desired saponification is attained and the mass appears as a transparent homogeneous liquid.

9pounds of alcohol or industrial methylated spirit are then added, and mixed thoroughly with the soap, which may then be removed from the vessel.

If a simple dry-cleaning soap is required,

this is mixed with four volumes of the sol- Example 2 In the preparation of hydrocarbons the ingredients should be in the following amounts 45.55 pounds of pure oleic acid (known as special pale frozen oleic acid 90.5 per cent to 1.00 per cent pure) or any similar oleic acid or oleine having a low setting point as specified are placed in a jacketed mechanical mixer and raised to a temperature of at least 170 Fahrenheit. To this is added an aqueous solution containing 11.38 pounds of pure potassium carbonate (99.5 to 100 per cent pure) or an equivalent amount of the hydroxides of potassium or sodium or liquid ammonia specific gravity 0.880. The solid alkalis should previously be dissolved in 15.56 pounds of boiling water. The alkaline solution should be added slowly until the fatty acids are completely saponified. Considerable ebullition takes place during saponificatio'n and when the mass, which should be homogeneous, with a transparent appearance, has subsided 27.51 pounds of pcrchlorethylene, pentachlorethane, or trichlorethylene, or the like, are added. Agitation is continued until the mixture is in a liquid state when it is removed from the vessel.

If a simple dry-cleaning soap is required, this is mixed with four volumes of the solvent used and the product constitutes a stock solution.

If a soap which is soluble in dry-cleaning fluid associated with a high percentage of moisture is required, a proportion of water is added to the aqueous solution of potassium carbonate. The total amount of water associated in this manner can be about one half or more by weight of oleic acid originally taken.

E mam-pie 3 In the preparation of 100 pounds of a neutral soa which is soluble in dry-cleaning fluid, whici is combined with cyclohexanol the ingredients should be in the proportions which will now be indicated.

45.55 pounds of oleic acid are placed in a jacketed mechanical mixer and raised to a temperature of at least 17 0 degrees Fahrenheit. Any reasonably pure oleic acid or oleine may be used but the setting point should be preferably below 60 Fahrenheit and to get the best results the more solid fatty components should set below- 36 F ahrenheit. To the heated fatty acid is added 11.38 pounds of pure potassium carbonate (99.5 to 100 per cent pure) or an equivalent amount of sodium carbonate or of the hydroxides of potassium or sodium or of liquid ammonia spccilic gravity 0.880. The solid alkalis should be previously dissolved in 15.56 pounds of boiling water and added slowly until the fatty acids are completely saponified. Considerable ebullition takes place during saponifieation and when the mass. which should be homogeneous, with a transparent appearance, has subsided 27.51 pounds of cyclohexanol are added. Agitation is continued until the mixture is in a liquid state when it is removed fromthe vessel.

Additional cvclohexanol may be added before, during or after saponification to increase the solvent action either in-water or in dry-cleaning fluid.

The cyclohexanol may be partly replaced by any of the chlorinated hydrocarbons hereinbet'ore mentioned but preferably by perchlorethylene. Convenient proportions range from 33 to 50 per cent of chlorinated hydrocarbon in the mixture.

If a simple dry-cleaning soap is required this is mixed with four volumes of the solvent used and the product constitutes a stock solution.

If a soap which is soluble in dry-cleaning fluid. associated with a high percentage of moisture is required, a proportion of water preferably equal or less than the oleic acid saponified, is added to the aqueous solution of potassium carbonate.

If a soap which is soluble both in drycleaning fluid and in water is required two or more volumes of solvent are added at the end of saponification. This solvent may be a fluid having a high boiling point, cyclohcxanol or chlorinated hydrocarbons as described.

It will be understood that while it is preferred to use practically pure oleic acid as the fatty acid the invention is not limited to any particular fatty acid and the term fatty acid in the claims is also intended to cover a mixture of fatty acids. It is also to he understood that where saponifying is used in the claims the action of wholly or 1 partially saponifying is designated.

' \Vhat we claim is 1. A process for manufacturing soap which is substantially completely soluble in dry-cleaning fluid, consisting in saponifying a fatty acid of which the setting point is below 60 degrees Fahrenheit with an alkaline solution, and incorporating therewith cyclohexanol as a stabilizing agent.

2. A process for manufacturing soap which is substantially completely soluble in dry-cleaning fluid or in water, consisting in saponifying 99.5 per cent pure oleic acid with an alkaline solution, and incorporating therewith cyclohexanol as a stabilizing agent.

3. A process for manufacturing soap which is completely soluble in dry-cleaning fluid or in water, consisting in saponifying 99.5 per cent pure olei'o acid with an alkaline solution, and incorporating therewith a mixture of cyclohexanol and a chlorinated hydrocarbon as stabilizing agent, substantially as described.

4. A cleaning composition comprising a fatty acid soap having a setting point below 60 Fahrenheit and an organic volatile liquid solvent incorporated therewith as a stabilizing agent.

5. A cleaning composition comprising a 99.5 per cent pure oleic acid soap and an organic volatile liquid solvent incorporated therewith as a stabilizing agent.

6. A cleaning composition comprising a 99.5 per cent pure oleic acid soap and cyclohexanol incorporated therewith as a stabilizing agent.

In testimony whereof we have signed our names to this specification.

ARTHUR EDWARD HATFIELD. EUSTACE ALEXANDER ALLIOTT.

5 CERTIFICATE OF CORRECTION.

Patent No. 1,728,342. Granted September 17, 192 9, to

ARTHUR EDWARD HATFIELD.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, line 96, after the compound word "dry-cleaning" and before the period insert the Words "solvents mentioned and in water"; page 2, line 129, strike out the word "spirit";

and that the said Letters Patent should be read with these corrections. therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 15th day of October, A. D. 1929.

M. J. Moore,

(Seal) Acting Commissioner of Patents. 

